Pump Assembly

ABSTRACT

A pump assembly as a feedback pump of a hydraulic, slip-controlled vehicle brake system having a piston pump and an electric motor for driving it is disclosed. The electric motor is embodied as an external rotor and the stator is mounted on a printed circuit board which has an electronic system for commutating the electric motor and/or for performing slip control of the vehicle brake system.

This application claims priority under 35 U.S.C. §119 to German patent application no. DE 10 2010 040 889.1, filed Sep. 16, 2010 in Germany, the disclosure of which is incorporated herein by reference in its entirety.

BACKGROUND

The disclosure relates to a pump assembly for a hydraulic vehicle brake system. It has a pump and an electric motor for driving it, which electric motor is connected to the pump to form the pump assembly.

Such pump assemblies are used as what are referred to as feedback pumps in slip-controlled hydraulic vehicle brake systems and in electro-hydraulic vehicle brake systems which are power-brake systems in which a brake pressure for performing service braking is built up with the pump assembly.

The utility model DE 20 2007 017 856 U1 discloses a miniature electric motor, with no purpose of use being specified. This electric motor has a disk-shaped rotor which is rotationally fixed to a motor shaft which is mounted with two bearings on each side of the rotor in a motor housing. A stator, specifically in particular stator windings, are arranged on a printed circuit board which is fixedly arranged in the motor housing, parallel to the rotor and with a small axial air gap with respect thereto. The motor shaft passes through a hole in the printed circuit board. The windings of the stator are applied to the printed circuit board as conductor tracks using thick film technology. Motor electronics are accommodated on the printed circuit board.

Laid-open patent application DE 10 2008 055 070 A1 discloses an eccentric gearing for driving a radial piston pump of a hydraulic assembly of a slip-controlled vehicle brake system. The eccentric gearing has a transmission shaft, a bearing ring which is mounted thereon with roller bearings, and roller bodies which are arranged in a gap between the transmission shaft and the bearing ring and which rotate around the transmission shaft when said shaft is driven in rotation, and roll on said shaft and in the bearing ring. The bearing ring is arranged eccentrically with respect to the transmission shaft, and the roller bodies have different diameters corresponding to a changing gap width between the bearing ring and the transmission shaft owing to the eccentricity of the bearing ring with respect to the transmission shaft. When the transmission shaft is driven in rotation, the changing gap width with the roller bodies runs around the transmission shaft and the bearing ring moves on an orbit about a rotation axis of the transmission shaft. The eccentric gearing converts a rotating drive movement of the transmission shaft into a to and fro reciprocating movement of pump pistons which are arranged radially with respect to the transmission shaft and bear with an end side on the outside of the bearing ring. The eccentricity of the bearing ring runs around more slowly than would correspond to a rotational speed of the transmission shaft, and the eccentric gearing has a step-down ratio, meaning that a reciprocating frequency of the pump pistons is lower than a rotational speed of the transmission shaft.

SUMMARY

The pump assembly, according to the disclosure, has a pump and an electric motor for driving it. The electric motor has a rotor, a stator and a printed circuit board. An electronic system can be arranged on the printed circuit board. This may be motor electronics for performing open-loop or closed-loop control, for example for performing electronic commutation of the electric motor. The printed circuit board can also have other electronics, for example for performing open-loop or closed-loop control of the hydraulic vehicle brake system for which the pump assembly is provided, that is to say, for example, slip control. For this reason, the printed circuit board does not have to be exclusively a printed circuit board of the electric motor, and there is provision, but this is not compulsory, for motor electronics of the electric motor to be arranged on the printed circuit board. As stated, other electronics can also be additionally or exclusively arranged on the printed circuit board.

The stator of the electric motor of the pump assembly according to the disclosure is mounted on the printed circuit board. In particular, coils of the stator are mounted on the printed circuit board. In particular, one or more sensors for sensing a rotation and/or a rotational position of the rotor of the electric motor in order to perform electronic commutation are also arranged on the printed circuit board.

The disclosure has the advantage of reducing installation space and costs. A further advantage of the disclosure is a short connection of coils of the stator of the electric motor to motor electronics or other electronics which are arranged on the printed circuit board. The connection is possible without plug-in connectors or other connectors, which excludes a probability of failure because of corroded connectors or connectors which have become loose automatically.

Advantageous refinements and developments of the disclosure are also set forth below.

BRIEF DESCRIPTION OF THE DRAWING

The disclosure will be explained in more detail below with reference to an exemplary embodiment which is illustrated in the drawing. The single drawing shows an axial section through a pump assembly according to the disclosure. The drawing is to be understood as a schematic and a simplified illustration for explaining and promoting understanding of the disclosure.

DETAILED DESCRIPTION

The pump assembly 1 which is illustrated in the drawing is provided as what is referred to as a feedback pump of a hydraulic, slip-controlled vehicle brake system. It has an electric motor 2 and a pump 3. The electric motor 2 is an electronically commutated brushless motor, but this is not absolutely necessary for the disclosure, for which other embodiments of electric motors can also be used. The electric motor 2 has a stator 4 with coils 5 which are arranged in an annular shape and are mounted on a printed circuit board 6. The printed circuit board 6 is arranged radially with respect to a virtual motor axis. An electronic system 7, symbolized by electronic components is arranged on the printed circuit board 6. The electronic system 7 comprises motor electronics for commutating the electric motor 2, and electronics for performing slip control of the hydraulic vehicle brake system, the pump assembly 1 forming a component thereof. These electronics can also be conceived of as an electronic control device of the hydraulic vehicle brake system. The printed circuit board 6 is equipped on both sides. A sensor 26 for sensing a rotation and/or a rotational position of the rotor 4 for the electronic commutation of the electric motor 2 is also attached to a side of the printed circuit board 6 facing the electric motor 2.

The electric motor 2 is what is referred to as an external rotor with a pole pot 8 which encloses the stator 4 coaxially. Permanent magnets 9 are attached to an inner circumference of the pole pot 8. An open end side of the pole pot 8 faces the printed circuit board 6, and a closed side of the pole pot 8 faces the pump 3. The pole pot 8 with the permanent magnet 9 forms a rotor 10 of the electric motor 2. The embodiment of the electric motor 2 as an external rotor permits a compact and installation-space-saving design of the electric motor 2 and of the pump assembly 1 overall. However, the design of an external rotor is not absolutely essential for the disclosure, the electric motor 2 can also have a different embodiment.

A shaft 11 is attached coaxially and protruding outward on an end side 12 of the pole pot 8. The shaft 11 can be conceived of as a motor shaft, transmission shaft and/or pump shaft and is occasionally also referred to below as such. The shaft 11 is rotatably mounted with two ball bearings 13 in a hydraulic block 14 which at the same time also forms a pump housing 15 of the pump 3. The electric motor 2 does not have its own bearing, its rotor 8 is exclusively mounted in a rotatable fashion with the two bearings 13 in the hydraulic block 14 or pump housing 15.

The pump assembly 1 or the pump 3 has, between the two bearings 13, an eccentric gearing 16 which, apart from the shaft 11, has roller bodies 17 and a bearing ring 18. As a component of the eccentric gearing 16 the shaft 11 can also be referred to as a transmission shaft. The bearing ring 18 encloses the shaft 11 in an axis-parallel and eccentric fashion, and a width of a gap between the bearing ring 18 and shaft 11 changes over the circumference. The roller bodies 17 have different diameters corresponding to the width of the gap between the bearing ring 18 and the shaft 11 at the location at which the respective roller body 17 is located. When the shaft 11 is driven in rotation, the roller bodies 17 roll on the shaft 11 and in the bearing ring 18 and run around the shaft 11. The position of the widest gap between the bearing ring 18 and the shaft 11 rolls around the shaft 11 with the roller body 17 with the largest diameter, and the position of the narrowest gap between the bearing ring 18 and shaft 11 roll around the shaft 11 with the roller body 17 with the smallest diameter, and any gap width between the bearing ring 18 and the shaft 11 runs around the shaft 11 likewise. The bearing ring 18 moves on a virtual orbit eccentrically with respect to the shaft 11, wherein the bearing ring 18 does not rotate, or at any rate does not have to rotate. The roller body 17 and with it the gap width between the bearing ring 18 and the shaft 11 run more slowly round the shaft 11 than would correspond to a rotational speed of the shaft 11. The movement of the bearing ring 18 on the orbit which is eccentric with respect to the shaft 11 is therefore also slower than would correspond to the rotational movement of the shaft 11.

The pump 3 is embodied as a piston pump and has two pump pistons 19 which are arranged opposite one another on the same axis, i.e. in what is referred to as a boxer arrangement. An axis of the piston pumps 19 intersects the axis and the rotational axis of the shaft 11. The piston pumps 19 are held in an axially displaceable fashion in pump drill holes 20 in the hydraulic block 14. Pump restoring springs 21 hold the pump pistons 19 in abutment on the outside of the bearing ring 18. In the illustrated exemplary embodiment, the restoring springs 21 are helical compression springs which are arranged on a side of the pump pistons 19 facing away from the eccentric gearing 16, in the pump drill holes 21. The movement of the bearing ring 18 on an orbit which is eccentric with respect to the shaft 11 when the shaft 11 is driven in rotation brings about a reciprocating movement of the pump pistons 19, as a result of which the pump pistons 19 take in brake fluid in a manner known per se through inlet valves 22 and expel it though outlet valves 23. This taking in and expulsion, i.e. the delivery of brake fluid with piston pumps is known per se and does not need to be explained in more detail here.

As a result of the relatively low speed of the movement of the bearing ring 18 on the orbit which is eccentric with respect to the shaft 11, compared to a rotational speed of the shaft 11, a step-down of the speed of the eccentric gearing 16 occurs, and a reciprocating frequency of the pump pistons 19 is lower than a rotational speed of the shaft 11. A step-down ratio results from the difference between the diameters of the roller bodies 17 and the diameter of the shaft 11, and high speed step-down ratios can be achieved. The eccentric gearing 16 converts a rotational movement of the shaft 11 into a translational movement, specifically the reciprocating movement of the pump pistons 19. The possible large step-down of the speed of the eccentric gearing 16 permits a high-speed and therefore small electric motor 2. For a given motor power, the electric motor 2 has a low motor torque owing to its high rotational speed, and this permits its stator 4 to be mounted on the printed circuit board 6.

The printed circuit board 6 is mounted on the hydraulic block 14 at a distance therefrom by means of spacer sleeves 24 and screws 25.

Hydraulic blocks such as the hydraulic block 14 of the pump assembly 1 according to the disclosure are known for slip-controlled hydraulic vehicle brake systems. Apart from the pump 3 with the pump pistons 19, further hydraulic components (not illustrated here) such as solenoid valves, hydraulic accumulators, dampers, non-return valves, pressure-limiting valves etc. are arranged and connected hydraulically to one another in such hydraulic blocks. The hydraulic components form hydraulic components of the slip-controlled device of the hydraulic vehicle brake system. Such hydraulic blocks are, as stated, known per se and will not be explained here in more detail. 

What is claimed is:
 1. A pump assembly for a hydraulic vehicle brake system, comprising: a pump; and an electric motor configured to drive the pump, wherein the electric motor has a rotor, a stator, and a printed circuit board, and wherein the stator is mounted on the printed circuit board.
 2. The pump assembly according to claim 1, wherein the stator has coils which are mounted on the printed circuit board.
 3. The pump assembly according to claim 1, wherein the electric motor is an external rotor.
 4. The pump assembly according to claim 3, wherein the rotor is coaxial and rigid with a shaft of the pump.
 5. The pump assembly according to claim 1, wherein the rotor of the electric motor is rotatably mounted in the pump.
 6. The pump assembly according to claim 1, wherein: the pump has eccentric gearing with a transmission shaft, a bearing ring which is mounted on rolling bearings on the transmission shaft and roller bodies which are arranged in a gap between the transmission shaft and the bearing ring, and the bearing ring is arranged eccentrically with respect to the transmission shaft, and the roller bodies have different diameters corresponding to a different gap width between the transmission shaft and the bearing ring.
 7. The pump assembly according to claim 1, wherein the pump is a piston pump. 